Blast-furnace



J. c. BENNETT. Blast Furnace. o. 242,1 o2. Patented May 31,1881.

I Wigwam fab-w UNITED STATES PATENT OFFICE.

JAMES C. BENNETT, OF CHICAGO, ILLINOIS.

BLAST-FURNACE.

SPECIFICATION forming part' of Letters Patent No. 242,102, dated May 31,1881.

' Application filed October 14, 1878.

To all whom it may concern:

Be it known that I, JAMES C. BENNETT, of Chicago, Cook county, Illinois,have invented certain new and useful Improvements in Blast- Furnaces, ofwhich the following is a specification.

My invention relates to an improvement in blast furnaces; and itconsists, first, in the method of preparing raw fuel and raw ore in acommon furnace-stack by subjecting them, while in contact with eachother, to a hot blast, and utilizing all the gaseous products therefromin the reduction of the metal in the lower part of the furnace in onecontinuous operation; second, in the construction of a blastfurnace,which is provided with suitable means for closing its top while inoperation, and an open bottom through which both the products ofcombustion and the reduced ore pass, a series of tuyeres extending upthe sides of the stack to its top, and in which stack the fire islighted in its bottom only, in contradistinction to its top, as has beendone heretofore where a downward draft has been used, whereby the wholecombustion of the fuel and reduction of the ore take place at or in thelower part of the furnace only.

The objects of my invention are, first, to prepare raw fuel and raw orein a common furnace-stack so as to dispense with the usual expensiveprocesses and machines heretofore used for the preparation of the oreand the fuel prior to their introduction into the furnace in which theore is to be reduced; second, to save and utilize, in the treatment andreduction of the ore in the furnace-stack, all of the gaseous productsgenerated by the hot blast in the charring of the wood, the coking ofthe coal, and the roasting of the ore; third, to secure a more complete,efficient, and economical reduction of ores, and a superior product in aless given time.

The accompanying drawing represents a vertical section of a furnacewhich embodies my invention.

A represents a common furnace-stack, which is provided at its'top with adouble chargingbell, G, or double doors or covers of any kind, which aregas -tight, and which have space enough between them to receive anddischarge an ordinary charge of fuel or of ore. This furnace ispreferably slightly reduced in size at its lower part, j, which isprovided with an enlarged opening through which both the products ofcombustion and reduction pass. Passing around this stack, near its lowerend, is a large blast-pipe, d, and from this pipe extend vertically anumber of smaller pipes, h, each one of which is provided with a numberof tuyeres, c, which pass into the stack from its outer side and astop-cock to each tuyere, so as to control the amount and force of theblast through it.

The tuyeres 0 may be placed closer together and a greater number of themused in the lower part of the furnace, where the combustion andreduction take place, than in the upper part of the furnace, where thefuel is prepared for combustion and the ore for reduction. The pipes andtuyeres extend entirely up to the top of the furnace, so that the hotblast can be introduced just under the bell, or at any point lower down,as the circumstances of the case may require.

In order to enable the workmen to inspect every operation of thefurnace, a small window of isinglass, or other equivalent substance, isplaced in each tuyere, through which the workman looks, and is thusenabled to judge where to turn 011 or turn on the blast.

The tuyeres are set facing each other on opposite sides of the stack, soas to facilitate the passage of the light, and thus enable the workmanto see through from side to side. Should he perceive that the reducedmetal is forming what is termed a scaffold in any part of the furnace,where the reduction of the ore takes place or elsewhere, he shuts offall of the blast from the tuyeres in the bottom of the furnace, andturns it on just above those points where the scaffold is adhering tothe inner walls of the stack, and these blasts produce such an intenseheat and action that the adhering portions of the scaffold are cut away.In this manner the workman is enabled to prevent any and allobstructions from forming, and he has every operation of the furnaceabsolutely under his control at all times.

In practice the furnace is charged and operated as follows: The stack isfirst filled with fuel, the devices for closing the top of the stackareopened,and thenthefireislighted atthebottom in the usual manner, andthis is continued until the lower portion of the furnace is filled witha solid mass of fire. During this preparatory stage no hot blast isused. The top of the furnace is then closed by the bell or other deviceprovided for this purpose, and alternate charges of ore and fuel arethen introduced in the usual manner and subjected to the operation ofthe hot blast, which is turned on as soon as the furnace is ready forwork. The lower part of the stack forms the zone of fusion, for at thispoint alone the combustion and reduction of the ore take place, whilethe upper part of the furnace forms the zone of prepation of the fuelfor combustion and the ore for reduction. It must be borne in mind thatno combustion takes place in the upper part of the furnace. The zone offusion is regulated by the workman, who, by turning on or shuting ofl"the tuyeres in the lower part of the furnace,has it always absolutelyunder his control. The zone of fusion is supplied with oxygen either inconnection with the hot blast or by any suitable device for thatpurpose. The upper part of the furnace, or the zone of preparation, iskept filled with raw fuel, raw ore, and a suitable flux mixed with theore, and the fuel and the ore are charged in from the top of the furnacein alternate layers. These layers of ore and fuel are subjected to theconstant action of the hot blast,which is admitted from the uppertuyeres, and this blast chars the wood or cokes the coal, thus preparingthem for combustion, and roasts and ealcines the ore for reduction. Asthese layers sink downward into the zone of fusion fresh layers arecharged in through the top of the furnace to take their place. Theconstant action of the hot blast on the fuel and ore, as they are incontact with each other in the stack, generates large amounts of gaseousproduct, which are driven downward into the zone of fusion by the blast,where they are consumed, and help to produce an intense heat,whichreduces the ore.

By thus preparing the fuel and roasting the ore in the stack not onlyare all of the gases generated utilized in the reduction of the ore, butall outside furnaces, ovens, and other such appliances as haveheretofore been used for this purpose done away with, but the ore isreduced much more quickly, and a much better product produced than inthe usual manner. It is evident that where the fuel has to be separatelyprepared in ovens, and the ore has to be roasted or calcined by itself,all of the gases generated therefrom by the heat are entirely lost, sofar as the reduction is concerned, and that the expense of handling thefuel and ore separately, and then burning them together after each onehas been prepared, is very large. All of these difficulties I entirelyovercome, for the ore and fuel are charged into the top of the stack ina raw state and in direct contact with each other, and their preparationand reduction take place in one continuous operation, which can becontinued for days or weeks without stopping the furnace, unlessdesired.

Where the ore needs further treatment, a reverberatory furnace, H, isconnected to the base of the stack by means of a covered passage-way,1). Through the side of this passage way is made a suitable opening, I,through which suitable tools can be introduced for the purpose oftransferring the metal directly into the reverberatory furnace from thebottom of the stack without exposing the metal to the action of theatmosphere.

I am aware that there is nothing new in the use of a furnace having aclosed top and a downward draft, and which has a reverberatory furnacein direct connection therewith, but in which the fire is lighted at thetop of the charge and the products of combustion driven down through theunconsumed and unreduced portion ofthe charge. Iam also aware that theuse of tuyeres in connection with a blast-furnace is old, and all theseI disclaim. My invention differs from all these in having my fire andthe point of reduction in the lower part of the stack, incontradistinction to a fire in the top of the furnace, and in using thetop part of my stack for preparing the fuel for combustion, and forroasting the ore by means of a downward hot blast.

My invention further differs from what has been done heretofore, inusing a common furnace-stack for preparing raw fuel for combustion, androasting raw ore while the fuel and ore are in direct contact with eachother, and utilizing the gaseous products derived from both ore and fuelin the reduction of the ore itself in the furnace-stack.

In short, by my new arrangement and combination of old devices andcontrivances I quicken and cheapen the cost of the reduction of the ore,and obtain, by a new and more direct mode of operation, the advantagesabove set forth.

I am also aware that it is not new to place fuel in a retort or furnacewhich is closed at its top, open at its bottom, and through which adownward blast is passed for the purpose of generating a gaseousproduct, which is to be used in the reduction of ore in an adjacentreverberatory furnace. My invention differs from this in placing the rawfuel and raw ore together in the same furnace, and burning the gaseousproducts in the same furnace in which they are generated and in whichthe ore is smelted.

Having thus described my invention, I claim- 1. The process hereindescribed of smelting ores, consisting in ehargin g the stack with rawore and raw fuel in direct contact with each other, closing the top ofthe furnace, admitting a hot blast, thereby coking or charring the fueland roasting the ore, and forcing the gaseous products generated by thehot blast from both fuel and ore down into the tire in the charged intothe furnace from its top upon the fire in its bottom, where thecombustion and reduction take place, substantially as set forth.

In testimony that I claim the foregoing I 15 have hereunto set my handthis 10th day of October, 1878.

JAMES C. BENNETT.

Witnesses:

T. F. LEHMANN, SAML. DIESGHER.

